Messages in this thread | | | From | David Howells <> | Subject | Re: [PATCH 4/9] KEYS: Allow unrestricted boot-time addition of keys to secondary keyring | Date | Thu, 17 Nov 2016 11:18:31 +0000 |
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Petko Manolov <petkan@mip-labs.com> wrote:
> > > Well, I for one do not explicitly trust these keys. I may even want to > > > completely remove or replace them. > > > > Fine be me. However, if you remove them all I would guess that you cannot > > perform a secure boot. > > Maybe not on PC, but there's plenty of other architectures out there. What > if i replace all UEFI keys with my own?
Then I would imagine that you can do a secure boot, but that you have to sign your own shim, grub, kernel, etc..
> > Note that it's to be expected that the keys being loaded from the UEFI > > database cannot have their signatures checked - which is why they would > > have to be implicitly trusted. For the same reason, the kernel does not > > check the signatures on the keys compiled into the kernel image. > > I build all kernels that matter to me and i _do_ trust myself. > Unfortunately i can't say the same for any corporation out there. > > Trusting a key because your vendor shipped the HW with it so that you have no > way to verify the signature is pretty weak argument IMHO.
I'm not making an argument there. There is a reason I think that I can't check them. Well, possibly I could *if* those keys are actually signed *and* I have certs built into the kernel by which I can verify all those keys in UEFI variables. I don't know whether this is actually practical.
> > You can argue this either way. There's a config option to allow you to > > turn this on or off. Arguably, this should be split in two: one for the > > whitelist (db, MokListRT) and one for the blacklist (dbx). > > I did not see the config option. There is one?
See patch 8 where these variables are actually parsed. CONFIG_LOAD_UEFI_KEYS is available there.
David
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